Conventional coated abrasive articles comprise a backing having a plurality of abrasive particles bonded to at least one major surface thereof by means of one or more binders (e.g., make, size, and supersize coats). Slurry coated abrasive articles, such as structured abrasive articles comprise a backing bearing on at least one major surface thereof an abrasive layer comprising a plurality of abrasive particles dispersed in a binder. For a structured abrasive, the abrasive layer is in the form of a plurality of shaped abrasive composites bonded to a backing. The backing can be paper, polymeric film, vulcanized fibre, nonwoven substrates, cloth, and combinations thereof. Cloth backings are typically either stitchbonded or woven. These backings are often treated with treatment coat(s) to seal the cloth and to protect the individual fibers. The particular treatment coat chemistry and weight will modify the physical properties of the resulting backing.
Cloths made from synthetic fibers (e.g., polyester, rayon, or nylon) are popular abrasive backings due to their strength, tear resistance, and/or flexibility. However, it is sometimes difficult to adhere binders and treatment coats properly to cloth backings. If these binders and treatment coats do not adhere properly, during abrading they will separate from the backing's fibers, which results in the release of abrasive particles. This phenomena is known in the abrasive art as shelling (i.e., the premature release of abrasive particles from the backing). In most cases, shelling is undesirable because it results in a loss of performance. What is desired by the abrasive industry is treating coats that will tenaciously adhere to fabrics. Besides the necessary adhesion between the treating coat and the yarns, the treating coat must also have adhesion to the binder in the abrasive layer. If there is poor adhesion between the treating coat and the abrasive binder, this can also lead to shelling.
For many years, conventional cloth backed coated abrasive articles utilized one or more treatment coats consisting of animal glues, starches, latices, thermally curable resins such as phenolic-based treatment coats or phenolic/latex treatment coats, and thermally cured phenolic-based binders in the abrasive coating. These combinations result in generally good adhesion between the treatment coat(s) and the fibers in the cloth backing and between the abrasive binder and the treatment coat(s). In recent years, some coated abrasive articles, particularly structured abrasive articles as disclosed in U.S. Pat. Nos. 5,152,917 (Pieper et al.) and 5,435,816 (Spurgeon et al.), have begun employing radiation cured binder systems, such as acrylate-based binders, in the abrasive layer instead of the phenolic-based binders. For some applications, the adhesion between conventional backing treatment coats, e.g., saturant coats, presize coats, and the like, and these new radiation cured binders is not as strong as desired, sometimes resulting in shelling, depending on the particular abrading application. This is true particularly if a continuous manufacturing process is used for making the abrasive article and relatively high processing speeds are used. Thus, what is needed is a system by which radiation cured binders, such as acrylate-based binders, can be used on treated cloth backings and produced in a continuous manufacturing process using relatively high processing speeds, with good adhesion.